Reenforced rubber article



Patented May 11', 1937 ATEN OFFICE k REENFORCED RUBBER ARTICLE John L.Bitter, Elizabethton, Tenn.,

North American Rayon Corporation,

N. Y., a corporationof Delaware assignor to New York,

'No Drawing. Application August 6, 1934,

Serial No. 738,690

(Claims. (Cl. %23) My present invention concerns a new method forpreparing threads of artificial .origin which may be employed in themanufacture of automobile tires and the like.

5 One object of the present invention is to pre-.

pare a synthetic thread which can be employed to I replace the cottonand otherthreads now in use in the automobile industry, and which willpossess characteristics peculiarly adapting it for such use.

7 There is between cellulose and rubber somewhat of a naturalincompatibility. The hydroxyl groups of the cellulose and thehydro-carbon structure peculiar to rubber act to repel one anotherrather than to unite. It has been found,

however, that carbon in the form of carbon black' possesses a naturalamnity for rubber. In accordance with my present invention, therefore, Iprepare a cellulosic solution and incorporate with it a quantity ofcarbon black. Unlike pigments, carbon does not lie inertlyin thesolution and'in the final filaments, but because of itssurface activityattracts, to some extent, the cellulose of the solution.

I am well aware th'at the incorporation of carbon black in a solution,for the purpose of giving it a dull or opaque appearance, has beensuggested. In that case, however,

was erroneously included in a group of so-called 30 inorganic pigmentlike particles. It is for its non-pigment-like properties that I am atpresent making use of this element. It will be especially noted that thehigh percentages of carbon black employed by me would actto produce anobjectionably colored filament when the ordinary use of such yarns isconsidered.

The exact chemical and physical action of carfbon with respect to rubberis not definitely known but several theories have beep advanced concern-40 ing this point. It is, probably ticles in. co-action with apronounced aflinity of carbon for the hydro-carbonfIclIaracteristics ofthe rubber. I have found thatwhem'artificial 4 filaments are prepared inaccordance'with myher and from 10 to 20% of carbon black is dumped intothe mixer containing the viscose. The perthe carbon black I bestexplained by the great surface activity of the carbon black parcentageiscalculated upon the weight of cellulose present in the solution. "Thissolution is then filtered and spun through ordinary 'spinnerettes.

The filaments contain, and have widely dispersedthroughout their mass,quantities of the carbonin o finely divided form. v

II. As an alternative method, I havefound that carbon black may bewetted with sodium hydroxide and may be mixed, or suspended, in aportion of the hydroxide prior to mixing the same 10 with the viscose.

III In the manufacture of cuprammonium filaments, cellulose is placed insolution in copperoxide-ammonia, and then this solution is spun in themanner described in Example I above. Siml ilarly, carbon may be includedin the form of carbon black in nitrocellulosic solutions and insolutions of cellulose esters and ethers.

- My new inventive concept may be also em:-

ployed with respect to the cotton or other threads 20 now being used inthe automobile industry. Cotton may be coated witl'r'a viscosesolutionprepared, for instance, as set forth in Example I. and thiscoated thread may be employed in the manufacture of the tire. The mannerin which this may be carried out is clearly set forth in the followingexample:

' IV. A viscose solution is prepared, as set forth in Example I, butinstead of extruding the solution, a cotton thread is passedtherethrough. The carbon impregnated viscose solution forms a coating onthe cotton and this coating is then fixed or precipitated by passing thethread directly into a bath. The threads thus coated may bedesulphurized and dried .or otherwise aftertreated in the known manner.I

. It has been found that cotton so treated is more compatible withrubber and thus a natural incompatibility between cellulose and rubberis overcome and a closer union between the treated 40 cotton and therubber in the finished product will result.

While I have mentioned the use of from 10-20% of carbon black, it is tobe understood that this proportion gives the best results without undulyweakening filaments to be spun from thesolution.

If too much carbon is employed the resulting filaments and. the threadsmade therefrom will be lacking pliability and tensile strength. Smallerpercentages of carbon, of course,- may be employed, but sufllcientshould be included to se- I cure a good union and co-action between thesynthetic material and the rubber.

The carbon content of the cellulose solution to be employed when cottonor other natural fiber i threads are coated as set forth in Example IVabove, maybe varied within greater limits than those Just described.This is evident from the fact that the tensile strength of the viscosecoatedfilaments could be treated for copper removal, etc.

Having now by the patent set forth my invention as required statutes.what I claim is:

1. A rubber article having embedded'therein strengthening threads of anartificial silk of the group consisting of regenerated celluloses, cellulose esters and cellulose ethers, said threads containing from about 10to 20% of a flnely divided carbon black calculated on their cellulosecontent.

2. A rubber article having embedded therein strengthening threads 01 a.regenerated cellulose, said threads containing from about 10 to 20% ofa. finely divided carbon black calculated on their cellulose content.

3. A rubber articlehaving embedded therein strengthening threads of acellulose ester, said threads containing from about 10 to 20% of afinely divided carbon black-calculated on their cellulose content.

4. A rubber article having embedded therein strengthening threads of acellulose ether, said threads containing from about 10 to 20% of afinely divided carbon blackcalculated on their cellulose content.

JOHN L. BITTER.

